The present invention relates to an improvement of a solar ray collecting device, in which solar rays are focused by a lens, guided into an optical fiber, and further transmitted through an optical conductor onto an appropriate desired place for use in illumination or for other purposes.
The present applicant has previously proposed a solar ray collecting device in which solar rays are focused by a lens or the like, guided into an optical conductor, and further transmitted through the optical conductor onto an appropriate desired place for use in illumination or for other purposes.
The solar ray collecting device previously proposed by the present applicant is comprised of a capsule comprising of a transparent dome-shaped head portion placed on a solar ray collecting portion which is accommodated in side of the capsule.
The solar ray collecting portion is comprised of a large number of lenses (for instance 19) arranged concentrically for collecting solar rays, a solar ray direction sensor for detecting the direction of the sun, a support frame for unitarily supporting the lenses and the sensor, a first motor for rotating the support frame together with the lenses and the sensor around a horizontal shaft, a vertical shaft installed perpendicular to the horizontal shaft for rotating the lenses, the sensor and the support frame, and a second motor for rotating the vertical shaft.
The solar ray direction sensor detects the direction of the sun and generates a detection signal. The above-mentioned first and second motors are controlled by the detection signal so as to always direct the lenses toward the sun. The solar rays focused by the lenses are guided, respectively, into a large number of optical conductor cables (19 cables for 19 lenses), the lightreceiving edges of which are arranged at the focal position of the lenses. Furthermore, the solar rays are transmitted through the optical conductor cables onto the optional desired place.
The solar ray collecting portion is accommodated inside of the capsule in the solar ray collecting device as mentioned above, for protecting the solar ray collecting portion from wind, rain, dust, etc. Therefore, a part of the solar rays are reflected on to the surface of the capsule. When the incidence angle is equal to or larger than the critical incidence angle, the solar rays are reflected totally on to the surface of the capsule so that they cannot reach the solar ray collecting portion.
In order to avoid such a troublesome inconvenience in the afore-mentioned solar ray collecting device, the capsule is formed in the shape of a sphere and therefore the solar rays enter into the capsule always in a uniform way regardless of which direction the light-receiving surface of the solar ray collecting portion is directed to. In addition, the diameter of the light-receiving surface of the solar ray collecting portion is so determined that the most externally-situated lens in the solar ray collecting portion is located in the area within the critical incidence angle. For this reason the entire construction of the solar ray collecting device, including the capsule, turns out to be large-scaled.
Further, the heat energy generated on the focal position of the lens may increase greatly because a Fresnel lens, having a large diameter, specifically 40 cm in diameter, is employed as a focusing lens. Therefore during the period when the solar ray collecting device is employed, the optical conductor cable and its support member are distorted by the accumulated heat energy so that the light-receiving surface of the optical conductor cable deviates from the focus of the lens and therefore the equilibrium of the relationship of the light-receiving surface position and the lens position must often be adjusted.